In the firing of industrial oil burners and auxiliary or igniter burners associated with large oil fired utility or industrial boilers, it is a conventional practice to employ steam as an atomizing agent for the fuel oil. Moreover, the same source of steam is usually employed in purging fuel oil lines for safety and other considerations. A combination valve of the type under consideration and Which controls the supply of both steam and fuel oil during firing and purging operations of burner systems is shown in U.S. Pat. No. 4,146,056 issued Mar. 27, 1979 and entitled STEAM AND FUEL OIL CONTROL AND PURGE VALVE. The valve shown and described in the patent, which is incorporated herein by reference, is particularly Well suited to the efficient control of firing and purge operations as aforesaid and is quite satisfactory in all respects. There is, however, one additional feature recently found desirable and which is lacking in the patented valve.
More particularly, if a burner "gun" is not retracted when removed from service while other "guns" are still in operation, the excessive heat encountered can do serious damage to the burner tip. It has been found, however, that it is possible to meter a small flow of steam through the gun and thus relatively "cool" the same and prevent damage thereto.
It is a general object of the present invention to provide a steam and fuel oil supply valve of the type mentioned and which includes a simple and straight- forward means providing for the supply of a metered flow of "cooling" steam to an inoperative burner "gun" and thus prevent damage thereto.